Method for processing heavy hydrocarbon feedstock

ABSTRACT

The method for processing heavy hydrocarbon feedstock, predominantly heavy crude oil, comprises pre-treatment of an initial feedstock and an auxiliary gaseous mixture at a pre-set pressure, introducing the pre-treated auxiliary gaseous mixture into the pre-treated feedstock and mixing thereof, cavitation treatment of the resulting mixture, separating liquid and gaseous products followed by isolating the final petroleum product. The novelty is in that gaseous hydrocarbons having the activation energy comparable with the molecule dissociation energy of the main components of the heavy hydrocarbon feedstock, are used as auxiliary gaseous mixture; and the pre-treatment of the initial heavy hydrocarbon feedstock and the auxiliary gaseous mixture, both of which are in the liquid state, is performed at a pressure which exceeds the saturated vapour pressure of the auxiliary gaseous mixture. The technical result is the improved physical and chemical characteristics of the final petroleum product by virtue of changing the composition and structure thereof, more particularly, by reducing its density, viscosity, and initial boiling point, by increasing the light fraction yield during refining, and by increasing the efficiency and the effectiveness factor of processing heavy hydrocarbon feedstock.

TECHNOLOGY AREA

This invention relates to oil refining, petrochemical and chemical as well as oil and energy industries, and specifically to the method of heavy raw hydrocarbons treatment and can be used in the preparation and processing of heavy oil, oil refinery and petrochemical industry residues, and other liquid hydrocarbon media for production of hydrocarbon fuel, petrochemicals and chemical products as well as for heavy oil transportation.

Pertinent as to Prior Art

The actual problem in transportation of heavy raw hydrocarbons (heavy crude oil) is to reduce its viscosity and density as well as to reduce the boiling point and increase the yield of light products during a refining process. Nowadays for heavy oil transportation it is usually diluted with light gasoline fractions (naphtha) before pumping it into a pipeline, while the volume of diluents can reach 15-20% of the heavy oil volume.

In case, when naphtha delivery to the terminal for oil dilution is not possible, then it is heated while transporting to reduce its viscosity.

The viscosity and density of heavy oil can also be decreased by its treatment in a cavitation reactor both in pure form and in the presence of auxiliary additives. The technology allows elimination or the significant reduction of the volume of diluents as well as to exclude heating or to reduce the temperature of the pipeline heating.

A method of heavy oil treatment is known, which includes oil preparation, auxiliary additives preparation, components mixing, cavitation treatment of the mixture where pentane is used as an auxiliary additive [1].

The disadvantage of this method is the process low efficiency due to the use of pentane as an auxiliary additive. The activation energy of pentane under the same temperature conditions is several times higher than the activation energy of high-molecular-weight components of heavy oil. Due to the significant difference in activation energies, the free radical concentration of light components in the mixture is much lower than the free radical concentration of heavy components. Fragments of oil high-molecular-weight components do not receive a sufficient amount of light radicals to react with them, so they recombine among themselves. Reduction of density and viscosity of heavy oil as for this treatment technology occurs mainly not due to the destruction of high-molecular-weight compounds of heavy oil, but due to its dilution with pentane.

The nearest to the proposed method for heavy raw hydrocarbons treatment is an oil treatment method [2], comprising oil preparation, an auxiliary additive (gas mixture) preparation, components mixing, their treatment in a cavitation reactor and liquid and gaseous products separation, where associated gas is used as an auxiliary additive (gas mixture). The jet-cavitation method is used for oil treatment with associated natural gas. At the same time, oil treatment with associated gas includes associated natural gas heating under the pressure of 0.6-0.8 MPa up to a temperature of 120° C., its acceleration to a supersonic speed greater than 400 m/s in the Laval nozzle expansion, oil flow acceleration under the pressure of 1.6 MPa at the temperature of 80-90° C. in a profiled channel and its spraying in a cavitation jet gas-liquid mixer to form a volumetric cavitation cavern, in which a supersonic natural gas flow is supplied coaxially and in the same direction with oil flow, thereby oil and gas flows interact and mix in a biphasic medium moving at local supersonic speed to get a mixture with gas concentration no less than 10% of the mass of oil being treated, the obtained mixture is directed along a profiled expanding channel where its velocity decreases and compaction surge occurs in passing through the sound barrier, in which natural gas dissolution in oil is completed, thereby in order to stabilize the mixture and remove excessive natural gas through the separator for reuse the repeated cavitation treatment in a passive cavitator-homogenizer is performed.

The drawbacks of using this method according to prototype are its high energy intensity, low oil treatment efficiency and the process low efficiency. In this case, oil high-molecular-weight components (fractions boiling in the temperature range of 350−550° C.) as well as their fragments have a comparatively high reactivity and easily enter into addition-oxidation reactions [3]. The associated gas contains mainly methane (70-96%), which as a representative of the simplest gaseous paraffinic hydrocarbons possesses high levels of chemical stability [4]. Consequently, the oil-gas working mixture in the reaction zone, even in the presence of catalysts must have the temperature of 350° C. at least. Cavitation treatment of associated gas mixture (according to the prototype) occurs at the temperature of 80-90° C. under maximum pressure of 1.6 MPa. This means that heavy hydrocarbon feedstock is in liquid state and methane is in gaseous state and the temperature is insufficient to activate it.

To enhance the reaction effect, it is necessary that the reacting components have comparable activation energy and, correspondingly, an approximately equal number of donors and acceptors among the formed free radicals. Failure to comply with the rule drastically reduces the process efficiency, which is the case in the prototype.

Invention Disclosure

The invention provides a method for processing heavy hydrocarbon feedstock that allows, in comparison with a prototype, to perform treatment of oil and petroleum products of high viscosity and density as fully and effectively as possible, improving physicochemical properties of final oil product by change in its composition and structure at low cost.

The invention objective is the process improvement of heavy raw hydrocarbons treatment, in which by using other auxiliary gas mixture and other conditions for preparation of the feedstock and auxiliary gas mixture, physicochemical parameters improvement of the treated heavy hydrocarbon feedstock is ensured by changing its composition, structure and high rate of heavy hydrocarbons conversion, in particular: decrease of density, viscosity, initial boiling point and increase of the light fractions yield during distillation, to increase the effectiveness of heavy hydrocarbon feedstock treatment and its efficiency, thereby foster the process energy consumption reduction.

The specified objective is achieved through the method of heavy raw hydrocarbons treatment, preferably heavy oil, including oil preparation, an auxiliary gas mixture preparation at given pressure, introduction of prepared auxiliary gas mixture to the feedstock and mixing of the same, the mixture cavitation treatment, liquid and gaseous products separation with the further final oil product extraction according to the invention, gaseous hydrocarbons having the activation energy comparable to molecules dissociation energy of major components of heavy raw hydrocarbons are used as auxiliary gas mixture, and preparation of the initial heavy hydrocarbon feedstock and auxiliary gas mixture being in the liquid state is performed under the pressure higher than the saturated vapor pressure of the auxiliary gas mixture.

Moreover, in some cases of using the claimed method of heavy raw hydrocarbons treatment, preferably heavy oil, the proposed method differs by:

-   -   heavy oil residues (residual fuel oil, tar, semi-tar), oil         sludge (asphalt-resin-paraffin deposits, fuel-oil, tank,         paraffin, etc.), used motor oils and lubricating oils, heavy         oil-containing fractions, heavy oils, mixtures: oil-mazut,         oil-semi-tar, oil-tar are used as heavy hydrocarbon feedstock in         various proportions;     -   gases of high-temperature catalytic cracking of oil and gas are         used as feedstock for the auxiliary gas mixture.

In general, the distinctive features of the claimed method for heavy raw hydrocarbons treatment are essential and necessary to achieve new technical result in comparison with the prototype.

The technical result is obtained as a result of the claimed invention use, which lies in improving the physicochemical parameters of the final oil product by changing its composition, structure, in particular, to decrease of its density, viscosity, boiling point, increase of the light fractions yield during distillation and increase of effectiveness of heavy raw hydrocarbons treatment and its efficiency.

The use of gaseous hydrocarbons having the activation energy comparable to molecules dissociation energy of major components of heavy raw hydrocarbons as an auxiliary gas mixture makes it possible to improve the physicochemical parameters of the final oil product, in particular, by increasing the yield of light fractions during distillation and lowering the boiling point, improvement in composition and structure is achieved as a result of density and viscosity decrease. A preliminary preparation of the heavy hydrocarbon feedstock and auxiliary gas mixture (auxiliary additive)—gaseous hydrocarbons being in the liquid state and having an activation energy comparable to molecules dissociation energy of major components of heavy raw hydrocarbons at the pressure higher than the saturated vapor pressure of the auxiliary gas mixture, provides high concentration of reacting components in a cavitation reactor. As a result of the mixture cavitation treatment of the pre-prepared heavy hydrocarbon feedstock and auxiliary gas mixture, due to the fact that the heavy hydrocarbon feedstock and auxiliary gas mixture have comparable activation energy, the necessary concentration of donor-acceptor free radicals is provided in the cavitation reactor. The maximum concentration of the donor-acceptor active molecules in the mixture being treated is the main principle of increasing the effectiveness of the desired product yield as a result of the cavitation effect on the mixture of the substances being treated under the selected conditions. In the process of the mixture cavitation treatment gasoline and light oil fractions are formed due to the destruction of high-molecular compounds of heavy raw hydrocarbons, and as a consequence, density and viscosity decrease of treated petroleum products occurs. The increase of gasoline and light oil fractions content leads to the boiling temperature decrease of treated heavy oil products and increase of the light fractions yield during distillation.

All this leads to improvement of physicochemical parameters of treated heavy hydrocarbon feedstock, and also increases the effectiveness of heavy oil products treatment and the process efficiency.

The absence of the preheating stage of the feedstock and auxiliary gas mixture, in comparison with the prototype, within the technological cycle of the proposed process for heavy hydrocarbon feedstock treatment, leads to decrease in the process energy intensity and increase in the effectiveness of heavy oil products treatment and its efficiency.

BRIEF DESCRIPTION OF DRAWINGS

The essence of the invention is illustrated by graphic materials,

FIG. 1 is the process flow chart of heavy hydrocarbon feedstock treatment,

FIG. 2 is the diagram showing heavy oil density change depending on percentage of the auxiliary gas mixture that is introduced into the feedstock before cavitation treatment, and

FIG. 3 is the diagram of heavy oil viscosity change depending on percentage of the auxiliary gas mixture that is introduced into the feedstock before cavitation treatment.

EXPECTED IMPLEMENTATION VARIANT OF INVENTION

The implementation variant of the proposed method of heavy raw hydrocarbons treatment is illustrated by the Process flow chart (see FIG. 1), where 1—feedstock, 2—auxiliary gas mixture, 3—prepared feedstock, 4—prepared gas mixture, 5—mixing of prepared feedstock 3 and auxiliary gas mixture 4, 6—cavitation treatment of mixture, 7—oil-gas separation, 8—finished oil product. In FIG. 2 and FIG. 3 the following is designated: 1—known (prototype), 2—proposed.

The claimed method of heavy raw hydrocarbons treatment, preferably heavy oil, can be realized using known standard equipment and devices in the industry.

The proposed method of heavy raw hydrocarbons treatment, preferably heavy oil, consists in the following: (see diagram in FIG. 1): feedstock 1 and auxiliary gas mixture 2 are prepared at specified pressure, for which they are compressed up to a pressure higher than the saturated vapor pressure of the auxiliary gas mixture. Then, prepared feedstock 3 and auxiliary gas mixture 4 are mixed 5, for example, in a mixer. Afterwards, cavitation treatment 6 of obtained mixture is performed in a cavitation machine. Subsequently, liquid and gaseous products are separated 7, for example, in an oil-gas separator with further releasing of final oil product 8 and gases unreacted that are returned to the tank for auxiliary gas mixture 2. In this case, gaseous hydrocarbons having an activation energy comparable to molecules dissociation energy of major components of heavy raw hydrocarbons are used as the auxiliary gas mixture 2, and the preparation of feedstock 1, 3 and auxiliary gas mixture 2, 4 being in the liquid state is performed at the pressure greater than the saturated vapor pressure of the auxiliary gas mixture 2.

The proposed method of heavy hydrocarbon feedstock treatment is performed by catalytic cracking in a cavitation reactor as follows. First, preliminary preparation of the heavy hydrocarbon feedstock and auxiliary gas mixture (additive) being in the liquid state is performed, what for they are fed from the storage tank to the feedstock preparation unit, where the feedstock is compressed to the specified pressure, which value is higher than the saturated vapor pressure of the auxiliary gas mixture.

Gaseous hydrocarbons are used as auxiliary gas mixture, which have an activation energy comparable to molecules dissociation energy of major components of heavy raw hydrocarbons. For example, if gaseous products of high-temperature cracking of oil and gas hydrocarbons are used as auxiliary gas mixture, the pressure shall not be lower than the saturated vapor pressure of propylene (the mixture component having the largest saturated vapor pressure of all the components), which is 1.132 MPa at 25° C. The higher the viscosity and density of the feedstock the greater the percentage of the auxiliary gas mixture (additive) that must contain the mixture before cavitation treatment.

Hydrodynamic cavitation units work efficiently, when liquids with the viscosity no greater than 5000 cSt are supplied to their intake. Based on this limitation, for the feedstock treatment with the viscosity of 20,000 cSt it is necessary to introduce auxiliary gas mixture of 2% by weight and for the feedstock treatment with the viscosity of 120,000 cSt it is necessary to introduce auxiliary gas mixture of 12 to 15% by weight.

After preparation the feedstock and auxiliary gas mixture (additive) are combined and mixed, for example, by feeding them into a mixer, where they are stirred in the liquid state.

After the prepared components mixing, the mixture is subjected to cavitation treatment by its feeding to a cavitation treatment unit, for example, hydrodynamic cavitation reactor, in which chemical reactions of heavy raw hydrocarbons catalytic cracking are performed in the presence of auxiliary gas mixture.

The pressure, at which the preparation and cavitation treatment of the mixture of the heavy hydrocarbon feedstock and auxiliary additive is performed, must be higher than the saturated vapor pressure of the auxiliary gas mixture, that is, gases shall be in the liquefied state.

As a result of cavitation treatment, the heavy hydrocarbon feedstock is catalytically cracked, where the hydrocarbons gas mixture having an activation energy comparable to molecules dissociation energy of major components of heavy raw hydrocarbons is used as auxiliary additive and cavitation is used as catalysator.

In the case of cavitation effect on the components mixture, when the bonds break energy of heavy hydrocarbon molecules and activation energy of the auxiliary gas mixture of hydrocarbons (additive) have similar values, the concentration of free radicals formed as a result of the destruction of heavy hydrocarbon molecules and free radicals of auxiliary substances will be the same with the appropriate selection of mass coefficients.

The viscosity and density decrease of heavy hydrocarbon feedstock is due to the decrease of average molecular weight of the hydrocarbon mixture, in which the content of gasoline and light oil fractions is increased after treatment.

After cavitation treatment the obtained mixture in the liquid state is fed to a separator, where the separation of liquid petroleum products (finished product) occurs from gases that have not reacted or formed in the process of treatment. Part of the gases after separation of low-boiling components—hydrogen, methane, ethane, etc. can be reused as feedstock for the auxiliary gas mixture preparation.

As a result, a finished petroleum product with improved physicochemical parameters is formed, in particular, with reduced density, viscosity, boiling point and increased yield of light fractions.

The invention effectiveness was tested on the cavitation machine IYJI-180 with the capacity up to 700 l/h and evaluated considering the change of heavy hydrocarbons physicochemical parameters before and after treatment, such as viscosity, density, initial boiling point, content of light fractions. The oil of the company Pacific Rubiales with parameters at 20° C.: density—0.976 g/cm³, viscosity—22500 cSt was used as heavy hydrocarbon feedstock. The initial boiling point was 242° C.

The effectiveness verification of using the proposed method for heavy hydrocarbons treatment, mainly heavy oil, was performed depending on the quantitative ratio of heavy oil products and auxiliary gas mixture.

Hydrocarbon gases having activation energy comparable to molecules dissociation energy of major components of heavy raw hydrocarbons were used as auxiliary gas mixture, in particular, the mixture of gases catalytic cracking with the propylene content of 65% at least, and total amount of unsaturated hydrocarbons not less than 80% by volume.

The heavy oil treatment was performed a single time in flow-through mode with the following parameters: initial temperature of 22-25° C., pressure of 1.6 MPa and feedstock performance of 450 l/h.

Heavy oil and auxiliary gas mixture at the pressure of 1.6 MPa were fed to the inlet of cavitation machine working chamber, where they were premixed.

Further, the mixture in the liquid state was fed into a working zone, where cavitation treatment took place, and then entered the receiving tank.

The quantity of formed products is determined by the feedstock physicochemical parameters (viscosity, density, fractional and group composition) and auxiliary additives (boiling point, saturated vapor pressure at operating temperature, degree of chemical bonds unsaturation), intensity of hydrodynamic oscillations and time while liquid remains in the treatment zone (performance). After finishing the cycle of heavy oil sample treatment, the excessive pressure was discharged from the system and the oil product was degassed until the residual dissolved gas content would be less than 1% by weight. The viscosity and density of the crude oil and obtained oil product as a result of treatment were measured after degassing at standard conditions (20° C.).

The results of experiments to determine changes in physicochemical parameters of heavy oil depending on the percentage of the auxiliary gas mixture introduced into heavy hydrocarbon feedstock before cavitation treatment, are presented in the table below.

Table

Change of heavy oil physicochemical parameters depending on the percentage of the auxiliary gas mixture introduced into feedstock before cavitation treatment

Change of heavy oil physicochemical parameters depending on the percentage of the auxiliary gas mixture introduced into feedstock before cavitation treatment

Amount of auxiliary gas mixture, which is introduced into feedstock before cavitation treatment, % by weight Method of treatment 0 2 4 6 8 10 Without treatment density, g/cm³ 0.976 viscosity, cSt 22,500 Known (prototype) density, g/cm³ 0.968 0.965 0.961 0.962 0.965 viscosity, cSt 16,000 15,000 14,000 13,500 13,000 Proposed density, g/cm³ 0.943 0.939 0.928 0.928 0.928 viscosity, cSt 4,200 3,000 2,400 2,200 2,000

The test results given in the table are also shown in the attached diagrams (see FIG. 2 and FIG. 3).

Based on the data presented in the attached diagrams the following conclusions can be generated.

At treatment of heavy oil of the company Pacific Rubiales, the oil density decreases after treatment according to the proposed method is 0.033-0.048 g/cm³, (average value—0.0405 g/cm³), and according to the prototype is 0.008-0.015 g/cm³, (average value—0.0115 g/cm³). Thus, the density change towards decrease in the proposed method is 3.5 times higher than in the prototype. The heavy oil viscosity after its treatment by the proposed method is decreased by more than 8 times and by the prototype in 1.6 times.

For comparing physicochemical parameters before and after heavy hydrocarbon feedstock treatment as well as determining the process effectiveness and efficiency, the oil by the company Pacific Rubiales before and after treatment was undergone by fractional distillation. As the tests showed, crude oil had the boiling point of 242° C., the light fractions yield of 55.5% by volume, prototype-treated oil had the boiling point of 181° C., the light fractions yield of 63%, and oil treated according to the proposed method had the boiling point of 127° C., the light fractions yield of 74.5% by volume.

INDUSTRIAL APPLICABILITY

The proposed method for processing heavy hydrocarbon feedstock can be used for multicomponent liquids treatment including modification of oil and petroleum products in order to improve their consumer properties, in particular, to reduce their viscosity and density. The invention is industrially applicable and can be put into effect by the methods implemented in industry using known means and equipment.

The performed tests showed that heavy oil treatment according to the proposed method allowed the density decrease by an average of 0.0405 g/cm³, viscosity by more than 8 times, reduce the boiling point by 115° C. and increase the light fractions yield of 19% by volume.

The foregoing demonstrates the possibility of the presented invention implementation and achievement of above mentioned technical result in the realization of the entire set of invention features described in the invention formula. The use of the entire set of the claimed invention essential features makes it possible to create a technology for heavy hydrocarbons treatment with improved consumer characteristics that are higher than in known ones at low energy intensity of the process and the process high efficiency.

The proposed method of heavy hydrocarbons treatment can be used for viscosity and density decrease before transportation through oil pipelines, and also increase of the light fractions yield during oil distillation.

INFORMATION SOURCES

-   1. U.S. Pat. No. 8,105,480 B2     C10G 9/00, priority from Mar. 6, 2007, published on Jan. 31, 2012. -   2. Patent RU 2436834,     C10G 015/00, C10G 04732, priority from 15 Mar. 2010, publication     date: 20 Dec. 2011 (prototype). -   3.     .     . B. A.     A. E.     . M.:     , 1995. C. 297 -   4. E. B.     2.     M.:     , 1980. C. 52. -   5.     .     C. K.     T. I.     :     , 1978. C. 67. 16 

1. Method for processing heavy hydrocarbon feedstock, especially heavy oil, which includes preparation of the feedstock and auxiliary gas mixture under given pressure, introduction of prepared auxiliary gas mixture to prepared feedstock and mixing of the same, cavitational treatment of the resulting mixture, separation of liquid and gaseous products with subsequent recovery of the finished petroleum product, which differs from others that gaseous hydrocarbons, having the activation energy comparable to molecules dissociation energy of major components of heavy raw hydrocarbons, are used as auxiliary gas mixture, and the preparation of heavy hydrocarbon feedstock and auxiliary gas mixture being in the liquid state is performed at higher pressure than the saturated vapor pressure of auxiliary gas mixture.
 2. The method of heavy raw hydrocarbons treatment according to claim 1, which differs from others that heavy oil residues are used as heavy hydrocarbon feedstock (masut, goudron, flux oil), oil sludge (asphalt, resin and paraffin deposition, fuel and lube, storage, paraffin etc.), used engine oils and lubricants, heavy oil-containing particles, heavy crude oils, mixtures: petroleum-masut, petroleum-flux oil, petroleum-goudron of various ratios.
 3. The method of heavy raw hydrocarbons treatment according to claim 1, which differs from others that natural gas or associated gas, or propane-butane mixtures, or gases of high temperature catalytic cracking of oil and gas are used as feedstock for auxiliary gas mixture. 